<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			*{
				margin: 0;
				padding: 0;
			}
			
			.box{
				width: 100%;
				height: 100px;
				border: 1px solid rosybrown;
			}
			.box div:nth-child(1){
				background-color: red;
			}
			.box div:nth-child(2){
				background-color: turquoise;
			}
			.box div:nth-child(3){
				background-color: cyan;
			}
			.box div:nth-child(4){
				width: 10%;
				height: 100px;
				background-color: pink;
			}
			
			.box div{
				float: left;
				width: 30%;
				height: 100px;
				
			}
			
		</style>
	</head>
	<body>
		<div class="box">
			<div>我占30%</div>
			<div>我占30%</div>
			<div>我占30%</div>
			<div>我占10%</div>
		</div>
	</body>
</html>